Method of removing skulls from metal receptacles



Aug. 14, 1951 I 5, v SLQTTMAN 2,564,037

METHOD OF REMOVING SKULLS FROM METAL RECEPTACLES Filed 001,. 28, 1947ATTORNEYS Patented Aug. 14, 19 51 METHOD OF REMOVING SKULLS FROM METALRECEPTACLES George V. Slottman, New York, N. Y., assignor to AirReduction Company, Incorporated, New York, N. Y., a corporation ol' NewYork Application October 28, 1947, Serial No. 782,532

2 Claims. 1

This invention relates to the treatment of ladles, mixers, and otherreceptacles employed in the handling of molten metals and particularlyto a method of preventing formation of and of removing skulls from suchreceptacles.

In the production of metals and alloys and especially in the steelindustry, receptacles gen-' erally referred to as ladles, mixers and thelike are employed in transferring molten metal and in other operations.From each successive charge of molten metal delivered to the receptacle,a portion chills and solidifies upon the bottom and walls. Gradually,accretion df metal forms a so-called skull which eventually reducessubstantially the capacity of the receptacle. Where considerablequantities of molten metals are handled, this loss of capacity mayreduce seriously the efllciency of operation.

Many attempts have been made heretofore to remove skulls from ladles,etc. The procedure usually involves chipping, which is expensive andoften destructive to the lining of the receptacle. Attempts have beenmade also to employ an oxyacetylene torch or lance to melt and burn theaccretions, but the results are not satisfactory. Damage to the liningof the receptacle frequently involves expensive and time-consumingrepairs.

It is the object of the invention to provide a method wherebyreceptacles for molten metal may be so treated periodically as toprevent the formation of or to remove skulls resulting from accretion ofsolid metal therein.

It is a further object of the invention to provide a method which may beapplied to receptacles of a variety of shapes and sizes and withoutdeleterious action upon the lining materials.

Other objects and advantages of the invention will be apparent as it isbetter understood by reference to the following specification and theaccompanying drawing, which illustrates in section a receptacle and themeans for eliminating the skull therefrom.

In accordance with the present invention, the skull is eliminated fromthe receptacle by the application of intensive heat, sufllcient to meltthe material forming the skull. The heat is applied by introducingoxygen to molten material, within the ladle, containing oxidizableconstituents. It is not necessary that the composition of the skull andof the molten material be the same. Skull formations usually comprisevarious constituents including metal and slag. The molten material maybe a part of the charge which the ladle or other receptacle is handling,or it may be special material introduced for the 2 purpose. Any materialhaving sufiicient quantities of oxidizable constituents and adapted toattain the necessary temperature may be used. All ferrous materialscontain silicon, manganese, carbon and iron, which are oxidizable in thepresence of oxygen. Molten iron from a blast furnace is ideal for thepurpose of the present invention, since it contains high percentages ofimpurities such as silicon, manganese and carbon. The iron itself isreadily oxidizable in the presence of oxygen. Hence, when oxygen isintroduced in sufficient quantity into the molten material, a hightemperature is developed with the resulting meltin of the skull. Themolten contents, at the completion of the operation, may be dischargedfrom the receptacle, leaving it clean and suitable for further use.

Obviously, the method may be practised in such a way as to preventsubstantial accretions and the formation of skulls by treating thereceptacle after each third or fourth operation, that is, after it hasbeen used in the ordinary manner as a container for molten metal. If,however, a substantial skull has formed, it may be eliminated readily inthe manner described.

Referring to the drawing, 5 indicates a ladle of the usual type whichconsists of a steel shell of sufficient strength to withstand thestresses to which it is subjected. Trunnions 6 permit the ladle to belifted by a crane or other apparatus adapted to facilitatetransportation. A lining I of suitable firebrick or other heat resistantmaterial is disposed within the receptacle. The shape and design of thereceptacle may vary, depending upon the particular purpose for which itis intended.

The skull 8 forms, as shown. in the bottom and on the sides of thereceptacle 5. If the material is permitted to accumulate, it willeventually fill the receptacle, which thereafter will be useless.Obviously, the formation of the skull reduces the capacity of thereceptacle.

To prevent the formation of such a skull or to eliminate it, a mass 9 ofmolten material containing oxidizable constituents is permitted toremain in the receptacle or is added thereto. Oxygen, from a suitablesource, is introduced through a pipe I 0 which may be connected by ahose l I to the source of supply. The oxygen may be substantially pure,that is to say, the oxygen of commerce, but it is not necessarily freefrom other gases such as nitrogen. Thus, a'mixture of nitrogen andoxygen containing 35% or more of oxygen will serve the purpose ofburning combustible elements in the molten mass 9. thus rapidlyproducing temperatures suflicient to melt the material forming the skull9.

When the skull has been melted, the molten material may be poured fromthe receptacle which is then clean and free for further use. Theoperation as indicated may be repeated at intervals to prevent accretionof material in the receptacle and the formation of a skull.

It is evident that the method as described may be applied easily toladies and mixers without the necessity of removing them from operationand that receptacles of almost any size or shape are adapted to thetreatment. The invention is particularly useful in types of receptacleshaving relatively small outlets so that the interior thereof is notreadily accessible.

Various changes may be made in the procedure as described and in theapparatus employed without departing from the invention or sacrificingthe advantages thereof.

Iclaim: i

1. The method of treating receptacles for molten metal to removeaccretions of solid materials therein which comprises adding molten pigiron to the receptacle and injecting oxygen into the molten pig iron toincrease its temperature and thereby melt the accretions.

2. The method of treating receptacles for 4 molten metals, whichreceptacles have accretiont of solid materials therein, which comprisesintroducing a mass of molten material comprising ferrous metalcontaining oxidizable constituents into the receptacle and injectinoxygen into the molten material to increase the temperature thereof andthereby melt the accretionsfi GEQRGE V. SLO'I'I'MAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 714,565 Dunford Nov. 25, 1902936,981 Brautigam Oct. 12, 1909 1,484,465 Billings Feb. 19, 19241,756,054 Crum Apr. 29, 1930 FOREIGN PATENTS Number Country Date 112,199Great Britain Jan. 3, 1918 OTHER REFERENCES Mellor: "Modern InorganicChemistry," revised edition. 1939, pages 807 and 808. Iongmans, Greenand 00., New York.

